Acoustical apparatus



May 28, 19%8 c. M. GUNDLACH 3,3853%4 ACOUSTI CAL APPARATUS Filed Sept.21, 1967 INVENTOR CHRiSTOPHER M. GUNDLACH y Wm, M A "*W Ams- UnitedStates Patent 3,385,394 ACOUSTICAL APPARATUS Christopher M. Gundlach,977 Ash St., Winnetka, Ill. 60093 Filed Sept. 21, 1967, Ser. No. 669,518Claims. (Cl. 18131) ABSTRACT OF THE DISCLOSURE A sound system for anelectrical organ includes a cabinet chamber through which sound isprojected into a listening area by one or more loudspeakers. A pair ofsoundreflecting baffles or vanes are rotated within the chamber atunequal speeds to produce a full, enveloping and nonpulsating sound.

The present invention relates to acoustical apparatus, and has for aprimary object the provision of an improved sound projecting system forelectrical organs, although the principles of the invention areapplicable to other types of sound systems.

Electrical organs of several types are known, and have becomeincreasingly popular because of their convenience, small size andreasonable cost. It is desirable that such organs be able to imitate asclosely as possible the sounds produced by a pipe organ, and in largepart they are successful in doing so. By producing, combining andregulating various tones electronically and/or mechanically, mostelectrical organs are capable of producing a sound which is quitesimilar to the sound produced by an organ pipe.

Although electrical organs can reproduce the sound of individual pipeorgan tones or notes, nevertheless they have not been able to reproducethe overall sound or effect of a pipe organ. A pipe organ, of course, isordinarily installed in a large space, and includes many sound sourcesspread over a large area. As a result, a pipe organ produces a big, fullsound having a largely omnidirectional effect upon a listener. The soundfrom the pipe organ thus seems to surround or envelope the listener.

Since the sound from electrical organs is projected from one or moreloudspeakers, the sound, particularly in the middle and high frequencyranges, is highly directional. Thus, the listener hears the sound from asingle point or region and the full sound of a pipe organ is lost. Someattempts have been made to overcome this problem, notably by the designof the loudspeaker enclosure or cabinet, by the use of several speakers,and by the use of various bafile arrangements. Known methods, however,have not been satisfactory and often are expensive. Arrangements usingone or more moving speakers or bafiles have been used to achieve arhythmic, pulsating, tremolo effect, but such arrangements have noteliminated the objectional directional characteristic of electricalorgan sounds.

It is therefore one important object of the present invention to providenovel acoustical apparatus for improving the sound produced byelectrical organs or other sound producing devices.

More particularly, it is an object of the invention to provide a novelsound system for eliminating or reducing the directional characteristicof the sound of an electrical organ, thereby to enlarge the sound sothat the sound of a pipe organ is more closely simulated.

Another object is to provide an apparatus and method for projecting ordistributing the sound from an electrical organ in a random and movingmanner.

A further object of the invention is to provide novel acousticalapparatus that can economically and conveniently be added to an organloudspeaker unit greatly to improve the sound quality thereof.

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In brief, the above and other objects and advantages of the presentinvention are achieved in one embodiment of the invention through theprovision of an organ sound system including one or more loudspeakersprojecting organ sound into a listening area by way of a speaker cabinetor enclosure. In accordance with an important feature of the inventionthe sound is projected throughout the listening area in a random andmoving manner to create a full, enveloping, non-pulsating effect bymeans of a pair of vanes positioned in the sound path within theenclosure and rotated at unequal speeds.

A more complete understanding of the invention together with its objectsand advantages may be had from the following detailed description ofcertain embodiments of the invention taken together with theaccompanying drawing, in which:

FIG. 1 is a perspective view of the speaker unit of an organ soundsystem constructed in accordance with the features of the invention,with part of the cabinet broken away;

FIG. 2 is a sectional view taken along the line 22 of FIG. 1;

FIG. 3 is an enlarged view of a control unit for the system;

FIG. 4 is a schematic representation of a circuit for controlling thesystem; and

FIG. 5 is a sectional view similar to FIG. 2 and illustrating analternative embodiment of the present invention.

Referring now to the drawing, there is illustrated an improved organsound system embodying the features of the present invention andincluding a speaker unit generally designated as 12 (FIGS. 1 and 2)together with a control unit generally designated as 14 (FIG. 3). Thespeaker unit 12 is adapted to be positioned in a room or [otherlistening area and interconnected to receive audio frequency electricalsignals from an electrical organ console and amplifier in the usualmanner. In accordance with the invention, the speaker unit 12 isprovided with a novel acoustical apparatus generally designated as 16and described in detail below. The apparatus 16 is controlled by thecontrol unit 14 which may be conveniently mounted beneath the organconsole keyboard 18.

Proceeding now to a description of the speaker unit 12, this unitincludes a cabinet or enclosure 20 which may be fabricated of wood inthe usual manner. An interior wall 22 subdivides the inside of thecabinet 20 into two chambers 24 and 26 intercommunicating by way of anopening 28 in the wall 22. Audio frequency signals are supplied from theelectrical organ console and amplifier through suitable wires (notshown) to an electroacoustical transducer in the form of a loudspeaker30 mounted in the chamber 24 on the wall 22 for projecting sound throughthe opening 28 and into the chamber 26. The cabinet 20 includes frontand side openings 32 and 34 covered by grille cloth 36 for allowingsound to escape from the chamber 26 into the listening area, although afront opening or openings alone could be used.

Conventional electrical organs suffer from the difficulty that thesound, especially in the middle and higher frequency ranges, is quitedirectional. Thus, throughout the listening area the listener hearsthese sounds principally from the direction of the loudspeaker, and thefull,

enveloping sound of a pipe organ is absent.

In accordance with an important feature of the present invention, theacoustical apparatus 16 includes a pair of baflle members or vanes 38and 4% moving at unequal speeds for projecting and distributing thesounds from the speaker 30 in a random and moving manner throughout thelistening area. This arrangement of at least two moving bafilesoperating at unequal speeds provides a full, enveloping, andnon-pulsating sound and reduces 3 or eliminates the directionalcharacteristic suffered with conventional electrical organs.

More specifically, the vanes 38 and 40 are mounted in side-by-siderelation in the chamber 26 and thus each vane is in the path of soundtravelling from the speaker 30 through the openings 32 and 34 to thelistening area. The vanes may be constructed of various materials, suchas sheet steel or wood, having sound reflecting properties. The vanesare mounted for rotation about parallel vertical axes by virtue of beingattached to a pair of spaced, rotatable drive shafts 42 and 44 bybrackets 46. The shafts 42 and 44 are drivingly connected to a pair ofdrive motors 4S and 50 carried on a support shelf 52 mounted on theinner wall 22.

Although many possible arrangements may be used for rotating the vanes38 and 40 at unequal speeds, in FIG. 4 there is illustrated one controlcircuit, generally designated as 54, for controlling the operation ofthe drive motors 48 and 59. As there illustrated, the drive motor 48 isconnected in series with an on-oif switch 56 between the terminals of asuitable electrical connector 58 adapted to be connected to a suitablepower supply, such as an outlet associated with the organ console andcontrolled by the main organ on-ofi switch. Whenever the circuit 54 isenergized and the switch 56 is closed, the motor 48 operates at apredetermined speed depending upon its design. In order to control theoperation of the second motor 50, the motor is connected in series withan on-otf switch 60 and also with a speed regulating device 62 which maybe of any known construction. When the control circuit 54 is energizedand the switch 60 is closed, the motor 50 operates at a speed determinedby the motor design and also by the setting of the speed regulatingdevice. Conveniently the manually operated controls of the circuit 54,i.e., the on-ofr' switches 56 and 60 and the speed control 62, aremounted on a control panel 64 positioned on the organ console asillustrated in FIG. 3 so as to be convenient to the player of the organ.Alternatively, of course, the controls may be associated with thespeaker unit 12.

It can now be seen that the control circuit 54 is capa ble of operatingthe drive motors at unequal speeds by adjustment of the speed control62. It has been found in devices constructed in accordance with theinvention that greatly improved sound quality is obtained when aplurality of baffles or vanes in the sound path are operated in thismanner. More specifically, the directional characteristic of the soundfrom the loudspeaker is overcome, and a full, enveloping sound is heard,without a pulsating tremolo.

Although there may be other factors creating this greatly improved soundquality, it is believed that the improvement is due at least in part tothe reflection of sound waves within the cabinet chamber 26 and tointeraction between the vanes moving at unequal speeds. It is known thatthe use of a single rotating vane produces merely a tremolo effectwithout elimination of the directional characteristic. However, when twovanes are moved at different speeds, a very different etfect is obtainedbecause there is no pulsating, tremolo effect and the directionalcharacteristic is eliminated or reduced. It is believed that theever-changing angles between the two vanes and between the vanes and thewalls causes the sound to be inter-reflected in a continuously varyingrandom pattern within the enclosure and from the enclosure into thelistening area.

Another embodiment of the invention is illustrated in FIG. wherein thereis shown a speaker unit 12' similar to the speaker unit 12 except thatit uses a pair of loudspeakers 66 and 68 rather than a singleloudspeaker. It has been found that like the embodiment of FIGS. 1-4,the arrangement of FIG. 5 produces a full, enveloping sound when thevanes are rotated at unequal speeds.

In one system constructed in accordance with the invention, verysatisfactory results were obtained by rotating one of the vanes atapproximately 30 revolutionsper minute and rotating the other vane atapproximately 35-50 revolutions per minute. These figures are given byway of example only and are not intended to limit the scope of theinvention as defined in the claims.

One advantage of the system of the present invention is that the speakerunit 12 can be used as the only speaker unit associated with the organconsole. Thus, if the switches 56' and 60 are both open the unit 12functions in the conventional manner. If only the switch 60 is closedthe vane 40 is rotated while the vane 38 remains stationary and atremolo or pulsating sound is achieved. Operation of the speedcontrol'62 determines the speed of rotation of the vane 40, thereby toregulate the speed or frequency of the tremolo efiect. V

The system of the present invention is also wellsuited for use with areverberation unit of any type, such as a spring-delay line unit or amagnetic tape unit. When the vanes 38 and 40 are moved at difierentspeeds and a reverberation unit is included in the system, anexceedingly realistic concert hall sound can be achieved.

An important advantage of the apparatus of the present invention is thatit can conveniently be added to existing organ speaker units. As will beapparent to those skilled in the art, this can be accomplished either bymodification of the existing speaker cabinet to provide a van containingchamber receiving sound from the speaker, or by the use of a separate,auxiliary cabinet placed in front of the existing cabinet.

While the present invention has been described in connection with thedetails of certain specific embodiments, other embodiments andequivalents may be devised which fall within the spirit and scope of theinvention. Consequently, it should be understood that the invention isnot limited by details of the described embodiment except as set forthin the following claims.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. Acoustical apparatus for use with a loudspeaker system of anelectrical organ or the like of the type including an enclosure,electro-acoust-ical transducer means for projecting sound into theenclosure, and at least one opening in the enclosure for allowing soundto escape from the enclosure into a listening area, said acousticalapparatus comprising first and second bafiies supported within saidenclosure, each in the path of sound waves traveling from the transducermeans to the listening area, first means for moving the first bafile ata first speed, and second means for moving the second bafile at a secondspeed unequal to the first speed.

2. The acoustical apparatus of claim 1, said first and second movingmeans including a first drive motor connected in driving relation to thefirst battle, a second drive motor connected in driving relation to thesecond baflie, and a motor control circuit connected to both said motorsfor operating said motors at diiferent speeds.

3. The acoustical apparatus of claim 2, said motor control circuitincluding an adjustable speed controlling device in circuit with saidfirst drive motor.

4. The acoustical apparatus of claim 1, each of said baffles including asubstantial surface area having sound reflecting properties, saidbaflies being mounted in sound inter-reflecting relationship with oneanother.

5. The acoustical apparatus of claim 1, each said bafile comprising asubstantially planar vane, a pair of parallel drive shafts one connectedto each vane, and said first and second moving means including means forrotating said shafts at different speeds.

6. An acoustical system for an organ and the like comprising:

a housing defining a chamber;

means including a loudspeaker for introducing sound waves into saidchamber;

an opening in said housing permitting sound waves to escape from saidchamber; 1

first and second baffie members mounted for movement within saidchamber; and means for moving said bafile members simultaneously atdifferent speeds thereby to produce a changing distribution of soundfrom said housing without tremolo. 7. The acoustical system of claim 6,said bafile members each comprising a substantially planar vane.

8. The acoustical system of claim 7, said vanes being mounted forrotational movement around parallel axes. 9. A method of improving theeffect of sound produced by an electrical organ and the like comprisingthe steps of:

projecting the sound from a speaker through a chamber to the listeningarea; rotating a first sound reflecting bafile member within the chamberat a first speed; and rotating a second sound reflecting baffle memberwithin the chamber at a second speed different from said first speed.10. Acoustical apparatus for use with a loudspeaker system of anelectrical organ or the like of the type ineluding an enclosureincluding wall means dividing the enclosure into first and secondintercommunicating chambers, a loudspeaker mounted in the first chamberfor projecting sound into the second chamber, and at least one openingin the enclosure for allowing sound to escape from the second chamberinto a listening area, said acoustical apparatus comprising first andsecond substantially rectangular and planar vanes formed of soundreflecting material, mounting means supporting said first and secondvanes in side-by-side relation within the secand chamber for rotationabout parallel axes, and drive means drivingly related to said first andsecond vanes for simultaneously rotating said vanes at difierent speeds.

References Cited UNITED STATES PATENTS 2,114,680 4/1938 Goldsmith 179-12,780,302 2/ 1957 George 181-31 3,095,069 6/ 1963 Hearne 181-3 13,266,592 8/ 1966 Leslie 181-27 STEPHEN J. TO-MSKY, Primary Examiner.

